Infantile nephrocalcinosis with chronic diarrhea.

A 3-month-old girl presented with symptoms indicative of dysuria, gross hematuria, chronic diarrhea, and nephrocalcinosis. She was born to fourth-degree consanguineous parents. The infant exhibited hypercalciuria and hyperoxaluria, and her stool tested positive for reducing sugars. She responded positively to dietary lactose restriction, and her hyperoxaluria improved over the course of 3 months. This suggests an enteric hyperoxaluria phenotype, although her hypercalciuria persisted. Whole exome sequencing identified a homozygous variant in the LCT gene, which is associated with congenital lactase deficiency, as well as a heterozygous variant in the ADCY10 gene, which is linked to absorptive hypercalciuria.